The present invention relates to an agitation method, an agitation mixer, and a feed pipe structure.
When manufacturing pharmaceutical products, chemical products, and food products, agitation is often performed to purify or separate a target compound. An agitation mixer used for such agitation typically includes an agitation vessel and an impeller arranged in the agitation vessel. The impeller agitates gases, liquids, solids, or a multiphase flow of these matters in the agitation vessel to cause various types of reactions, such as crystallization and polymerization.
Crystallization is one of separation-purification processes and includes re-crystallizing or precipitating crystal grains from a supersaturated solution. Further, crystallization is a method for not only precipitating a target substance but also for purifying grains having a target property, such as a desirable grain diameter. When purifying gains, a solution is agitated by an agitation mixer to disperse the grains in a liquid (solvent) and produce solid-liquid multiphase slurry. The slurry is then filtered and dried to obtain the desired solid grains. Precipitation purification is one example of crystallization performed with polymer grains. In precipitation purification, a poor solvent is added to a polymer solution to prepare a slurry. Then, the slurry is filtered and dried to obtain solid polymer grains (refer to Japanese Laid-Open Patent Publication No. 2005-320444, Japanese Laid-Open Patent Publication No. 2004-29254, and Japanese Laid-Open Patent Publication No. 2001-139692).
From the viewpoint of the amount that can be processed, it is preferable that continuous processing be performed instead of batch processing when performing agitation during a manufacturing process. FIG. 9 shows a main body 100 of a conventional continuous processing type agitation mixer. The main body 100 is connected to a first feed pipe 101, which is for feeding a first liquid (e.g., polymer solution P). A second feed pipe 102 for feeding a second liquid (e.g., poor solvent S) is connected to the first feed pipe 101 just before the main body 100. Accordingly the main body 100 is fed with a liquid mixture of the polymer solution P and the poor solvent S. The liquid mixture of the polymer solution P and the poor solvent S is agitated in the main body 100 and then discharged from the main body 100 through a discharge pipe 103.